Manufacture of refractory materials



unrreo siarrs PATENT @FFHCE.

JAMES F. MOLLEN, 0F CLEVELAND, AND WALTER W. FATNOE, 0F TIFFIN, OHIO,

ASSIGNORS TO THE DOLOMITE PRODUCTS COMPANY,

CORIPQRATION OF OHIO.

0F CLEVELAND, 0310, A

MANUFACTURE OF REFRACTORY MATERIALS.

No Drawing.

To all whom it may concern:

Be it known that we, JAMES F. MOLLEN and WALTER W. PATNOE, both citizensof the United States, and residents of Cleveland,

county of Cuyahoga, and State of Ohio, and of Tifiin, county of Seneca,and State of Ohio, respectively, have jointly invented a new and usefulImprovement in the Manufacture of Refractory Materials, of which thefollowing is a specification, the principle of the invention beinghereinexplained and the best mode in which we have contemplated applyingthat principle, so as to distinguish it from other inventions.

The improved refractory material, forming the subject matter of thepresent invention, is more particularly designed for'use as a lining forfurnaces such as are employed in steel manufacture, for example suchmaterial being on the order of that described and claimedin UnitedStates Letters Patent No, 1,230,430, to George W. Patnoe, as consistingof the granular product resulting from the calcination of a mixture offinely divided magnesian limestone and a small percentage ofargillaceous matter containing iron oxid. A further and quite importantaspect of the present invention is an improvement in the process ofmanufacturing a material of the character just described.

To the accomplishment of the foregoing and related ends, the invention,then, consistsof the steps hereinafter fully described and particularlypointed out in the claims,

the following description setting forth in detail one approved method ofcarrying out the process, suhdisclosed mode, however, constituting butone of the various ways in which the principle of the invention may beused. Claims'to the specific composition of matter herein disclosed havebeen incorporated in our co-pending divisional apR lication filedSeptember 23. 1920, Serial 0. 412,227, the present case being limited,as indicated, to the process aspect of the invention.

As in the case of the furnace lining material which forms the subjectmatter of the aforesaid patent, in carrying out the present invention wepreferably take a relatively pure magnesian limestone or dolomite, andrender it dense and stable by incorporating therewith a certain smallpercentage of fluxing material, which preferably consists ofepecification of "Letters Patent. Patgnj gfl Jam, 11 1921. Applicationfiled February 2, 1920. Serial No. 355,689.

silica, alumina and iron oxid, inclusively referred to as argillaceousmaterial. The specific differences in the proportions of the ngredientsin the finished product will be subsequently set forth; but as a typicalanalysis of the ingredients employed, we give thefollowing, viz. 91 percent. of raw dolomite composed of magnesium carbonate and calciumcarbonate in the relative proportions of 45 per cent. and per cent; percent. of iron oxid, such as haematite ore; and 3% per cent. of fireclay. 1

As in the case of such previously patente product, the principal step intheprocess of manufacture is the calcination of the raw dolomite ormagnesian limestone, to which has been added the proper amount offluxing materials, such calcination being accomplished in a rotary kilndisposed at a slightly inclined axis similar to that regularly em ployedin the calcination of ordinary limestone. The raw material, includingthe fluxing agents in question, is preferably finely ground with theaddition of water preliminarily to its introduction at one end of suchkiln, the mixture being sufiiciently dilute to form a slurry. Theinitial effect of the heat, combined with the rotative movement of thekiln is to cause this material to form mud balls or lumps, andheretofore difficulty has been experienced, whatever the proportion offluxing materials used, in that such balls or lumps tend to disintegrateand reduce to powder, and the material is thus in the form of dust whenit reaches the hottest zone at the farther end of the furnace, where thetemperature is from 2600 to 3000 F. This condition is objectionable,inasmuch as the preferred form of the material is that of a granularsintered product resulting from the calcination of the foregoingingredients.

We have found the objectionable condition referred to can be entirelyeliminated if, to the ingredients previously enumerated, there be addedfrom one to five per cent. of common salt (sodium chlorid),approximately 3-} per cent. giving-the best results, with the exactproportion of other ingredients thus enumerated. This salt seems to havea. mechanical or physical efi'ect merely,

rendering the slurry heavier or denser, and so causing it to form welldefined and distinct globules or nodules which will remain intact untilthe sintering stage is reached.

The addition of the relatively small amount of salt, in other words,will completely do away with the objectionable dusting, and cause thematerial to come through as a clean granular product at the dischargeend of the furnace. The salt is apparently entirely driven out by theheat, none being left in such product, except the merest trace, so thatits action would appear to be other than a chemical one.

A typical analysis of the finished product, made from the raw materialsin the proportions previously indicated, and by the process justdescribed, is as follows, viz. lime 50.3 per cent, magnesia 34 percent., silica 3.54 per cent, alumina 2.12 per cent, and iron oxid 8.13per cent, the balance being accounted for by a trace of manganesemonoxid and the loss incidental to analysis.

Other modes of applying the principle of our invention may be employedinstead of the one explained, change being made as'regards the methodherein disclosed, provided the steps stated by any of the followingclaims or the equivalent of such stated steps be employed.

WV e therefore particularly point out and distinctly claim as ourinvention 1. In a method of making a refractory material suitable forfurnace linings and the like, the steps which consist in making a slurryof raw dolomite, adding a small percentage of common salt, and thenpassing I the mixture through a rotary kiln operated at a temperaturesufficiently high to calcine such dolomite and drive off practically allof such salt.

2. In a method of making a refractory material suitable for furnacelinings and the like, the steps which consist in making a slurry of rawdolomite admixed with a small percentage 7 of argillaceous matter addinga small, percentage of common salt, and then passing the mixture througha rotary kiln operated at a temperature sufficiently high to calcinesuch dolomite and drive off practically all of such salt.

3. In a method of making a refractory memes material suitable forfurnace linings and the like, the steps which consist in making a slurryof raw dolomite admixed with a small percentage of argillaceous matter,adding from one to five per cent. of common salt, and then passing themixture through a rotary kiln operated at a temperature sufficientlyhigh to calci-ne such dolomite and drive off practically all of suchsalt.

-4. In a method of makin a refractory material suitable for furnaceinings and the like, the steps which consist in making a slurry of rawdolomite, admixed with approximately ten per cent. of argillaceousmatter, adding a small percentage of common salt, and then passing themixture through a rotary kiln operated at a temperature sufficientlyhigh to calcine such dolomite and drive off practically all of suchsalt.

5. In a method of making a refractory material suitable for furnacelinings and the like, the steps which consist in making a slurry of rawdolomite, admixed with approximately six per cent. of iron oxid and fourper cent. of fire clay, adding from one to five per cent. of commonsalt, and then passing the mixture through a rotary kiln operated at atemperature sufficiently high to calcine such dolomite and drive offpractically all of such salt.

6. In a method of making a refractory material suitable for furnacelinings and the like, the steps which consist in making a slurry of rawdolomite, admixed with approximately six per cent. of iron oxid and fourper cent. of fire clay, adding approximately three and one half percent. of common salt, and then passing the mixture through a rotary kilnoperated at a temperature sufficiently high to calcine such dolomite anddrive off practically all of such salt.

Signed by JAMES F. MoLLnN, this 29 day of January, 1920.

JAMES F. MOLLEN.

Signed by \V ALTER I PATNOE, this 29 day of January, 1920.

.VVALTER- WV. PATNOE.

